// Copyright 2006 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.


// Known Issues: (From VML version)
//
// * Patterns are not implemented.
// * Radial gradient are not implemented. The VML version of these look very
// different from the canvas one.
// * Coordsize. The width and height attribute have higher priority than the
// width and height style values which isn't correct.
// * Painting mode isn't implemented.
// * Canvas width/height should is using content-box by default. IE in
// Quirks mode will draw the canvas using border-box. Either change your
// doctype to HTML5
// (http://www.whatwg.org/specs/web-apps/current-work/#the-doctype)
// or use Box Sizing Behavior from WebFX
// (http://webfx.eae.net/dhtml/boxsizing/boxsizing.html)
// * Optimize. There is always room for speed improvements.

//Known Issues: Silverlight version
//
// * Doing a transformation during a path (ie lineTo, transform, lineTo) will
// not work corerctly because the transform is done to the whole path (ie
// transform, lineTo, lineTo)
// * Patterns are not yet implemented.


// only add this code if we do not already have a canvas implementation
if (!window.CanvasRenderingContext2D) {

    (function () {
    
    var xamlId;
    
    var G_vmlCanvasManager_ = {
    init: function (opt_doc) {
    var doc = opt_doc || document;
    // Create a dummy element so that IE will allow canvas elements to be
    // recognized.
    doc.createElement('canvas');
    if (/MSIE/.test(navigator.userAgent) && !window.opera) {
    var self = this;
    
    createXamlScriptTag();
    
    doc.attachEvent('onreadystatechange', function () {
    self.init_(doc);
    });
    }
    },
    
    init_: function (doc) {
    // setup default css
    var ss = doc.createStyleSheet();
    ss.cssText = 'canvas{display:inline-block;overflow:hidden;' +
    // default size is 300x150 in Gecko and Opera
    'text-align:left;width:300px;height:150px}' +
    'canvas *{width:100%;height:100%;border:0;' +
    'background:transparen;margin:0}' +
    'canvas div {position:relative}' +
    // Place a div on top of the plugin.
    'canvas div div{position:absolute;top:0;' +
    // needs to be "non transparent"
    'filter:alpha(opacity=0);background:red}';
    
    // find all canvas elements
    var els = doc.getElementsByTagName('canvas');
    for (var i = 0; i < els.length; i++) {
    if (!els[i].getContext) {
    this.initElement(els[i]);
    }
    }
    },
    
    
    /**
    * Public initializes a canvas element so that it can be used as canvas
    * element from now on. This is called automatically before the page is
    * loaded but if you are creating elements using createElement you need to
    * make sure this is called on the element.
    * @param {HTMLElement} el The canvas element to initialize.
    * @return {HTMLElement} the element that was created.
    */
    initElement: function (el) {
    el.getContext = function () {
    if (this.context_) {
    return this.context_;
    }
    return this.context_ = new CanvasRenderingContext2D_(this);
    };
    
    var attrs = el.attributes;
    if (attrs.width && attrs.width.specified) {
    // TODO: use runtimeStyle and coordsize
    // el.getContext().setWidth_(attrs.width.nodeValue);
    el.style.width = attrs.width.nodeValue + 'px';
    } else {
    el.width = el.clientWidth;
    }
    if (attrs.height && attrs.height.specified) {
    // TODO: use runtimeStyle and coordsize
    // el.getContext().setHeight_(attrs.height.nodeValue);
    el.style.height = attrs.height.nodeValue + 'px';
    } else {
    el.height = el.clientHeight;
    }
    
    // insert object tag
    el.innerHTML = getObjectHtml();
    
    // do not use inline function because that will leak memory
    el.attachEvent('onpropertychange', onPropertyChange);
    return el;
    }
    };
    
    function onPropertyChange(e) {
    var el = e.srcElement;
    
    switch (e.propertyName) {
    case 'width':
    el.style.width = el.attributes.width.nodeValue + 'px';
    el.getContext().clearRect();
    break;
    case 'height':
    el.style.height = el.attributes.height.nodeValue + 'px';
    el.getContext().clearRect();
    break;
    }
    }
    
    G_vmlCanvasManager_.init();
    
    function createXamlScriptTag() {
    // This script tag contains the boilerplate XAML.
    document.write('<script type=text/xaml>' +
    '<Canvas x:Name="root" ' +
    'xmlns="http://schemas.microsoft.com/client/2007" ' +
    'xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" ' +
    'Width="300" ' +
    'Height="150" ' +
    'Background="Transparent"> ' +
    '</Canvas>' +
    '</script>');
    // Find the id of the writtenscript file.
    var scripts = document.scripts;
    var script = scripts[scripts.length - 1];
    xamlId = script.uniqueID;
    script.id = xamlId;
    }
    
    function getObjectHtml(fn) {
    return '<div><object type="application/x-silverlight" >' +
    '<param name="windowless" value="true">' +
    '<param name="background" value="transparent">' +
    '<param name="source" value="#' + xamlId + '">' +
    '</object><div></div></div>';
    }
    
    function hasSilverlight() {
    try {
    new ActiveXObject('AgControl.AgControl');
    return true;
    } catch(_) {
    return false;
    }
    }
    
    // precompute "00" to "FF"
    var dec2hex = [];
    for (var i = 0; i < 16; i++) {
    for (var j = 0; j < 16; j++) {
    dec2hex[i * 16 + j] = i.toString(16) + j.toString(16);
    }
    }
    
    function createMatrixIdentity() {
    return [
    [1, 0, 0],
    [0, 1, 0],
    [0, 0, 1]
    ];
    }
    
    function matrixMultiply(m1, m2) {
    var result = createMatrixIdentity();
    
    for (var x = 0; x < 3; x++) {
    for (var y = 0; y < 3; y++) {
    var sum = 0;
    
    for (var z = 0; z < 3; z++) {
    sum += m1[x][z] * m2[z][y];
    }
    
    result[x][y] = sum;
    }
    }
    return result;
    }
    
    function doTransform(ctx) {
    transformObject(ctx, getRoot(ctx), ctx.m_);
    }
    
    function transformObject(ctx, obj, m) {
    var transform = obj.renderTransform;
    var matrix;
    if (!transform) {
    transform = create(ctx, '<MatrixTransform/>');
    matrix = create(ctx, '<Matrix/>');
    transform.matrix = matrix;
    obj.renderTransform = transform;
    } else {
    matrix = transform.matrix;
    }
    
    matrix.m11 = m[0][0];
    matrix.m12 = m[0][1];
    matrix.m21 = m[1][0];
    matrix.m22 = m[1][1];
    matrix.offsetX = m[2][0];
    matrix.offsetY = m[2][1];
    }
    
    function copyState(o1, o2) {
    o2.fillStyle = o1.fillStyle;
    o2.lineCap = o1.lineCap;
    o2.lineJoin = o1.lineJoin;
    o2.lineWidth = o1.lineWidth;
    o2.miterLimit = o1.miterLimit;
    o2.shadowBlur = o1.shadowBlur;
    o2.shadowColor = o1.shadowColor;
    o2.shadowOffsetX = o1.shadowOffsetX;
    o2.shadowOffsetY = o1.shadowOffsetY;
    o2.strokeStyle = o1.strokeStyle;
    o2.globalAlpha = o1.globalAlpha;
    o2.arcScaleX_ = o1.arcScaleX_;
    o2.arcScaleY_ = o1.arcScaleY_;
    }
    
    // precompute "00" to "FF"
    var decToHex = [];
    for (var i = 0; i < 16; i++) {
    for (var j = 0; j < 16; j++) {
    decToHex[i * 16 + j] = i.toString(16) + j.toString(16);
    }
    }
    
    // Silverlight does not support spelling gray as grey.
    var colorData = {
    darkgrey: '#A9A9A9',
    darkslategrey: '#2F4F4F',
    dimgrey: '#696969',
    grey: '#808080',
    lightgrey: '#D3D3D3',
    lightslategrey: '#778899',
    slategrey: '#708090'
    };
    
    
    function getRgbHslContent(styleString) {
    var start = styleString.indexOf('(', 3);
    var end = styleString.indexOf(')', start + 1);
    var parts = styleString.substring(start + 1, end).split(',');
    // add alpha if needed
    if (parts.length == 4 && styleString.substr(3, 1) == 'a') {
    alpha = +parts[3];
    } else {
    parts[3] = 1;
    }
    return parts;
    }
    
    function percent(s) {
    return parseFloat(s) / 100;
    }
    
    function clamp(v, min, max) {
    return Math.min(max, Math.max(min, v));
    }
    
    function hslToRgb(parts){
    var r, g, b;
    h = parseFloat(parts[0]) / 360 % 360;
    if (h < 0)
    h++;
    s = clamp(percent(parts[1]), 0, 1);
    l = clamp(percent(parts[2]), 0, 1);
    if (s == 0) {
    r = g = b = l; // achromatic
    } else {
    var q = l < 0.5 ? l * (1 + s) : l + s - l * s;
    var p = 2 * l - q;
    r = hueToRgb(p, q, h + 1 / 3);
    g = hueToRgb(p, q, h);
    b = hueToRgb(p, q, h - 1 / 3);
    }
    
    return decToHex[Math.floor(r * 255)] +
    decToHex[Math.floor(g * 255)] +
    decToHex[Math.floor(b * 255)];
    }
    
    function hueToRgb(m1, m2, h) {
    if (h < 0)
    h++;
    if (h > 1)
    h--;
    
    if (6 * h < 1)
    return m1 + (m2 - m1) * 6 * h;
    else if (2 * h < 1)
    return m2;
    else if (3 * h < 2)
    return m1 + (m2 - m1) * (2 / 3 - h) * 6;
    else
    return m1;
    }
    
    function translateColor(styleString) {
    var str, alpha = 1;
    
    styleString = String(styleString);
    if (styleString.charAt(0) == '#') {
    return styleString;
    } else if (/^rgb/.test(styleString)) {
    var parts = getRgbHslContent(styleString);
    var str = '', n;
    for (var i = 0; i < 3; i++) {
    if (parts[i].indexOf('%') != -1) {
    n = Math.floor(percent(parts[i]) * 255);
    } else {
    n = +parts[i];
    }
    str += decToHex[clamp(n, 0, 255)];
    }
    alpha = parts[3];
    } else if (/^hsl/.test(styleString)) {
    var parts = getRgbHslContent(styleString);
    str = hslToRgb(parts);
    alpha = parts[3];
    } else if (styleString in colorData) {
    return colorData[styleString];
    } else {
    return styleString;
    }
    return '#' + dec2hex[Math.floor(alpha * 255)] + str;
    }
    
    function processLineCap(lineCap) {
    switch (lineCap) {
    case 'butt':
    return 'flat';
    case 'round':
    return 'round';
    case 'square':
    default:
    return 'square';
    }
    }
    
    function getRoot(ctx) {
    return ctx.canvas.firstChild.firstChild.content.findName('root');
    }
    
    function create(ctx, s, opt_args) {
    if (opt_args) {
    s = s.replace(/\%(\d+)/g, function(match, index) {
    return opt_args[+index - 1];
    });
    }
    
    try {
    return ctx.canvas.firstChild.firstChild.content.createFromXaml(s);
    } catch (ex) {
    throw Error('Could not create XAML from: ' + s);
    }
    }
    
    function drawShape(ctx, s, opt_args) {
    var canvas = ctx.lastCanvas_ || create(ctx, '<Canvas/>');
    var shape = create(ctx, s, opt_args);
    canvas.children.add(shape);
    transformObject(ctx, canvas, ctx.m_);
    if (!ctx.lastCanvas_) {
    getRoot(ctx).children.add(canvas);
    ctx.lastCanvas_ = canvas;
    }
    return shape;
    }
    
    function createBrushObject(ctx, value) {
    if (value instanceof CanvasGradient_) {
    return value.createBrush_(ctx);
    } else if (value instanceof CanvasPattern_) {
    throw Error('Not implemented');
    } else {
    return create(ctx, '<SolidColorBrush Color="%1"/>',
    [translateColor(value)]);
    }
    }
    
    /**
    * This class implements CanvasRenderingContext2D interface as described by
    * the WHATWG.
    * @param {HTMLElement} surfaceElement The element that the 2D context should
    * be associated with
    */
    function CanvasRenderingContext2D_(surfaceElement) {
    this.m_ = createMatrixIdentity();
    this.lastCanvas_ = null;
    
    this.mStack_ = [];
    this.aStack_ = [];
    this.currentPath_ = [];
    
    // Canvas context properties
    this.strokeStyle = '#000';
    this.fillStyle = '#000';
    
    this.lineWidth = 1;
    this.lineJoin = 'miter';
    this.lineCap = 'butt';
    this.miterLimit = 10;
    this.globalAlpha = 1;
    this.canvas = surfaceElement;
    };
    
    
    var contextPrototype = CanvasRenderingContext2D_.prototype;
    
    contextPrototype.clearRect = function() {
    var root = getRoot(this);
    root.children.clear();
    
    // TODO: Implement
    this.currentPath_ = [];
    this.lastCanvas_ = null;
    
    };
    
    contextPrototype.beginPath = function() {
    // TODO: Branch current matrix so that save/restore has no effect
    // as per safari docs.
    
    this.currentPath_ = [];
    };
    
    contextPrototype.moveTo = function(aX, aY) {
    this.currentPath_.push('M' + aX + ',' + aY);
    };
    
    contextPrototype.lineTo = function(aX, aY) {
    if (this.currentPath_.length == 0) return;
    this.currentPath_.push('L' + aX + ',' + aY);
    };
    
    contextPrototype.bezierCurveTo = function(aCP1x, aCP1y,
    aCP2x, aCP2y,
    aX, aY) {
    if (this.currentPath_.length == 0) return;
    this.currentPath_.push('C' + aCP1x + ',' + aCP1y + ' ' +
    aCP2x + ',' + aCP2y + ' ' +
    aX + ' ' + aY);
    };
    
    contextPrototype.quadraticCurveTo = function(aCPx, aCPy, aX, aY) {
    if (this.currentPath_.length == 0) return;
    this.currentPath_.push('Q' + aCPx + ',' + aCPy + ' ' +
    aX + ',' + aY);
    };
    
    contextPrototype.arcTo = function(x1, y1, x2, y2, radius) {
    if (this.currentPath_.length == 0) return;
    // TODO: Implement
    };
    
    contextPrototype.arc = function(aX, aY, aRadius,
    aStartAngle, aEndAngle, aClockwise) {
    var deltaAngle = Math.abs(aStartAngle - aEndAngle);
    // If start and stop are the same WebKit and Moz does nothing
    if (aStartAngle == aEndAngle) {
    // different browsers behave differently here so we do the easiest thing
    return;
    }
    
    var endX = aX + aRadius * Math.cos(aEndAngle);
    var endY = aY + aRadius * Math.sin(aEndAngle);
    
    if (deltaAngle >= 2 * Math.PI) {
    // if larger than 2PI
    this.arc(aX, aY, aRadius, aStartAngle, aStartAngle + Math.PI, aClockwise);
    this.arc(aX, aY, aRadius, aStartAngle + Math.PI,
    aStartAngle + 2 * Math.PI, aClockwise);
    // now move to end point
    this.moveTo(endX, endY);
    return;
    }
    
    var startX = aX + aRadius * Math.cos(aStartAngle);
    var startY = aY + aRadius * Math.sin(aStartAngle);
    var rotationAngle = deltaAngle * 180 / Math.PI; // sign, abs?
    var sweepDirection = aClockwise ? 0 : 1;
    var isLargeArc = rotationAngle >= 180 == Boolean(aClockwise) ? 0 : 1;
    
    if (this.currentPath_.length != 0) {
    // add line to start point
    this.lineTo(startX, startY);
    } else {
    this.moveTo(startX, startY);
    }
    
    this.currentPath_.push('A' + aRadius + ',' + aRadius + ' ' +
    rotationAngle + ' ' +
    isLargeArc + ' ' +
    sweepDirection + ' ' +
    endX + ',' + endY);
    };
    
    contextPrototype.rect = function(aX, aY, aWidth, aHeight) {
    this.moveTo(aX, aY);
    this.lineTo(aX + aWidth, aY);
    this.lineTo(aX + aWidth, aY + aHeight);
    this.lineTo(aX, aY + aHeight);
    this.closePath();
    };
    
    contextPrototype.strokeRect = function(aX, aY, aWidth, aHeight) {
    // Will destroy any existing path (same as FF behaviour)
    this.beginPath();
    this.moveTo(aX, aY);
    this.lineTo(aX + aWidth, aY);
    this.lineTo(aX + aWidth, aY + aHeight);
    this.lineTo(aX, aY + aHeight);
    this.closePath();
    this.stroke();
    this.currentPath_ = [];
    };
    
    contextPrototype.fillRect = function(aX, aY, aWidth, aHeight) {
    // Will destroy any existing path (same as FF behaviour)
    this.beginPath();
    this.moveTo(aX, aY);
    this.lineTo(aX + aWidth, aY);
    this.lineTo(aX + aWidth, aY + aHeight);
    this.lineTo(aX, aY + aHeight);
    this.closePath();
    this.fill();
    this.currentPath_ = [];
    };
    
    contextPrototype.createLinearGradient = function(aX0, aY0, aX1, aY1) {
    return new LinearCanvasGradient_(aX0, aY0, aX1, aY1);
    };
    
    contextPrototype.createRadialGradient = function(x0, y0,
    r0, x1,
    y1, r1) {
    return new RadialCanvasGradient_(x0, y0, r0, x1, y1, r1);
    };
    
    contextPrototype.drawImage = function (image, var_args) {
    var dx, dy, dw, dh, sx, sy, sw, sh;
    
    // For Silverlight we don't need to get the size of the image since
    // Silverlight uses the image original dimension if not provided.
    
    if (arguments.length == 3) {
    dx = arguments[1];
    dy = arguments[2];
    // Keep sx, sy, sw, dw, sh and dh undefined
    } else if (arguments.length == 5) {
    dx = arguments[1];
    dy = arguments[2];
    dw = arguments[3];
    dh = arguments[4];
    // Keep sx, sy, sw and sh undefined
    } else if (arguments.length == 9) {
    sx = arguments[1];
    sy = arguments[2];
    sw = arguments[3];
    sh = arguments[4];
    dx = arguments[5];
    dy = arguments[6];
    dw = arguments[7];
    dh = arguments[8];
    } else {
    throw Error('Invalid number of arguments');
    }
    
    var slImage;
    
    // If we have a source rect we need to clip the image.
    if (arguments.length == 9) {
    slImage = drawShape(this, '<Image Source="%1"/>', [image.src]);
    
    var clipRect = create(this,
    '<RectangleGeometry Rect="%1,%2,%3,%4"/>', [sx, sy, sw, sh]);
    slImage.clip = clipRect;
    
    var m = createMatrixIdentity();
    
    // translate to 0,0
    m[2][0] = -sx;
    m[2][1] = -sy;
    
    // scale
    var m2 = createMatrixIdentity();
    m2[0][0] = dw / sw;
    m2[1][1] = dh / sh;
    
    m = matrixMultiply(m, m2);
    
    // translate to destination
    m[2][0] += dx;
    m[2][1] += dy;
    
    transformObject(this, slImage, m);
    
    } else {
    slImage = drawShape(this,
    '<Image Source="%1" Canvas.Left="%2" Canvas.Top="%3"/>',
    [image.src, dx, dy]);
    if (dw != undefined || dh != undefined) {
    slImage.width = dw;
    slImage.height = dh;
    slImage.stretch = 'fill';
    }
    }
    };
    
    contextPrototype.stroke = function() {
    if (this.currentPath_.length == 0) return;
    var path = drawShape(this, '<Path Data="%1"/>',
    [this.currentPath_.join(' ')]);
    path.stroke = createBrushObject(this, this.strokeStyle);
    path.opacity = this.globalAlpha;
    path.strokeThickness = this.lineWidth;
    path.strokeMiterLimit = this.miterLimit;
    path.strokeLineJoin = this.lineJoin;
    // Canvas does not differentiate start from end
    path.strokeEndLineCap = path.strokeStartLineCap =
    processLineCap(this.lineCap);
    };
    
    contextPrototype.fill = function() {
    if (this.currentPath_.length == 0) return;
    var path = drawShape(this, '<Path Data="%1"/>',
    [this.currentPath_.join(' ')]);
    // The spec says to use non zero but Silverlight uses EvenOdd by defaul
    path.data.fillRule = 'NonZero';
    path.fill = createBrushObject(this, this.fillStyle);
    path.fill.opacity = this.globalAlpha;
    // TODO: What about even-odd etc?
    };
    
    contextPrototype.closePath = function() {
    this.currentPath_.push('z');
    };
    
    /**
    * Sets the transformation matrix and marks things as dirty
    */
    function setM(self, m) {
    self.m_ = m;
    self.lastCanvas_ = null;
    };
    
    contextPrototype.save = function() {
    var o = {};
    copyState(this, o);
    this.aStack_.push(o);
    this.mStack_.push(this.m_);
    setM(this, matrixMultiply(createMatrixIdentity(), this.m_));
    };
    
    contextPrototype.restore = function() {
    copyState(this.aStack_.pop(), this);
    setM(this, this.mStack_.pop());
    };
    
    contextPrototype.translate = function(aX, aY) {
    var m1 = [
    [1, 0, 0],
    [0, 1, 0],
    [aX, aY, 1]
    ];
    
    setM(this, matrixMultiply(m1, this.m_));
    };
    
    contextPrototype.rotate = function(aRot) {
    var c = Math.cos(aRot);
    var s = Math.sin(aRot);
    
    var m1 = [
    [c, s, 0],
    [-s, c, 0],
    [0, 0, 1]
    ];
    
    setM(this, matrixMultiply(m1, this.m_));
    };
    
    contextPrototype.scale = function(aX, aY) {
    var m1 = [
    [aX, 0, 0],
    [0, aY, 0],
    [0, 0, 1]
    ];
    
    setM(this, matrixMultiply(m1, this.m_));
    };
    
    contextPrototype.transform = function(m11, m12, m21, m22, dx, dy) {
    var m1 = [
    [m11, m12, 0],
    [m21, m22, 0],
    [ dx, dy, 1]
    ];
    
    setM(this, matrixMultiply(m1, this.m_));
    };
    
    contextPrototype.setTransform = function(m11, m12, m21, m22, dx, dy) {
    setM(this, [
    [m11, m12, 0],
    [m21, m22, 0],
    [ dx, dy, 1],
    ]);
    };
    
    contextPrototype.clip = function() {
    if (this.currentPath_.length) {
    var clip = this.currentPath_.join(' ');
    var canvas = create(this, '<Canvas Width="%1" Height="%2" Clip="%3"/>',
    [getRoot(this).width, getRoot(this).height, clip]);
    var parent = this.lastCanvas_ || getRoot(this);
    
    parent.children.add(canvas);
    this.lastCanvas_ = canvas;
    }
    };
    
    contextPrototype.createPattern = function() {
    return new CanvasPattern_;
    };
    
    // Gradient / Pattern Stubs
    function CanvasGradient_() {
    this.colors_ = [];
    }
    
    CanvasGradient_.prototype.addColorStop = function(aOffset, aColor) {
    aColor = translateColor(aColor);
    this.colors_.push({offset: aOffset, color: aColor});
    };
    
    CanvasGradient_.prototype.createStops_ = function(ctx, brushObj, colors) {
    var gradientStopCollection = brushObj.gradientStops;
    for (var i = 0, c; c = colors[i]; i++) {
    var color = translateColor(c.color);
    gradientStopCollection.add(create(ctx,
    '<GradientStop Color="%1" Offset="%2"/>', [color, c.offset]));
    }
    };
    
    function LinearCanvasGradient_(x0, y0, x1, y1) {
    CanvasGradient_.call(this);
    this.x0_ = x0;
    this.y0_ = y0;
    this.x1_ = x1;
    this.y1_ = y1;
    }
    LinearCanvasGradient_.prototype = new CanvasGradient_;
    
    LinearCanvasGradient_.prototype.createBrush_ = function(ctx) {
    var brushObj = create(ctx, '<LinearGradientBrush MappingMode="Absolute" ' +
    'StartPoint="%1,%2" EndPoint="%3,%4"/>',
    [this.x0_, this.y0_, this.x1_, this.y1_]);
    this.createStops_(ctx, brushObj, this.colors_);
    return brushObj;
    };
    
    function isNanOrInfinite(v) {
    return isNaN(v) || !isFinite(v);
    }
    
    function RadialCanvasGradient_(x0, y0, r0, x1, y1, r1) {
    if (r0 < 0 || r1 < 0 || isNanOrInfinite(x0) || isNanOrInfinite(y0) ||
    isNanOrInfinite(x1) || isNanOrInfinite(y1)) {
    // IE does not support DOMException so this is as close as we get.
    var error = Error('DOMException.INDEX_SIZE_ERR');
    error.code = 1;
    throw error;
    }
    
    CanvasGradient_.call(this);
    this.x0_ = x0;
    this.y0_ = y0;
    this.r0_ = r0;
    this.x1_ = x1;
    this.y1_ = y1;
    this.r1_ = r1;
    }
    RadialCanvasGradient_.prototype = new CanvasGradient_;
    
    CanvasGradient_.prototype.createBrush_ = function(ctx) {
    if (this.x0_ == this.x1_ && this.y0_ == this.y1_ && this.r0_ == this.r1_) {
    return null;
    }
    
    var radius = Math.max(this.r0_, this.r1_);
    var minRadius = Math.min(this.r0_, this.r1_);
    var brushObj = create(ctx, '<RadialGradientBrush MappingMode="Absolute" ' +
    'GradientOrigin="%1,%2" Center="%3,%4" ' +
    'RadiusX="%5" RadiusY="%5"/>',
    [this.x0_, this.y0_, this.x1_, this.y1_, radius]);
    
    var colors = this.colors_.concat();
    
    if (this.r1_ < this.r0_) {
    // reverse color stop array
    colors.reverse();
    for (var i = 0, c; c = colors[i]; i++) {
    c.offset = 1 - c.offset;
    }
    }
    
    // sort the color stops
    colors.sort(function(c1, c2) {
    return c1.offset - c2.offset;
    });
    
    if (minRadius > 0) {
    // We need to adjust the color stops since SL always have the inner radius
    // at (0, 0) so we change the stops in case the min radius is not 0.
    for (var i = 0, c; c = colors[i]; i++) {
    c.offset = minRadius / radius + (radius - minRadius) / radius * c.offset;
    }
    }
    
    this.createStops_(ctx, brushObj, colors);
    return brushObj;
    };
    
    function CanvasPattern_() {}
    
    // set up externs
    G_vmlCanvasManager = G_vmlCanvasManager_;
    CanvasRenderingContext2D = CanvasRenderingContext2D_;
    CanvasGradient = CanvasGradient_;
    CanvasPattern = CanvasPattern_;
    
    })();
    
    } // if